18F-Fluorocholine PET Whole-Body MRI in the Staging of High-Risk Prostate Cancer

ACR Appropriateness Criteria® Pretreatment Detection, Surveillance, and Staging of Prostate Cancer: 2022 Update

Prostate cancer is second leading cause of death from malignancy after lung cancer in American men. The primary goal during pretreatment evaluation of prostate cancer is disease detection, localization, establishing disease extent (both local and distant), and evaluating aggressiveness, which are the driving factors of patient outcomes such as recurrence and survival. Prostate cancer is typically diagnosed after the recognizing elevated serum prostate-specific antigen level or abnormal digital rectal examination. Tissue diagnosis is obtained by transrectal ultrasound-guided biopsy or MRI-targeted biopsy, commonly with multiparametric MRI without or with intravenous contrast, which has recently been established as standard of care for detecting, localizing, and assessing local extent of prostate cancer. Although bone scintigraphy and CT are still typically used to detect bone and nodal metastases in patients with intermediate- or high-risk prostate cancer, novel advanced imaging modalities including prostatespecific membrane antigen PET/CT and whole-body MRI are being more frequently utilized for this purpose with improved detection rates. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

The Role of [18F]F-Choline PET/CT in the Initial Management and Outcome Prediction of Prostate Cancer: A Real-World Experience from a Multidisciplinary Approach

Initial staging of prostate cancer (PCa) is usually performed with conventional imaging (CI), involving computed tomography (CT) and bone scanning (BS). The aim of this study was to analyze the role of [¹⁸F]F-choline positron emission tomography (PET)/CT in the initial management and outcome prediction of PCa patients by analyzing data from a multidisciplinary approach. We retrospectively analyzed 82 patients who were discussed by the uro-oncology board of the University Hospital of Ferrara for primary staging newly diagnosed PCa (median age 72 (56-86) years; median baseline prostate specific antigen (PSA) equal to 8.73 ng/mL). Patients were divided into three groups based on the imaging performed: group A = only CI; group B = CI + [¹⁸F]F-choline PET/CT; group C = only [¹⁸F]F-choline PET/CT. All data on imaging findings, therapy decisions and patient outcomes were retrieved from hospital information systems. Moreover, we performed a sub-analysis of semiquantitative parameters extracted from [¹⁸F]F-choline PET/CT to search any correlation with patient outcomes. The number of patients included in each group was 35, 35 and 12, respectively. Patients with higher values of initial PSA were subjected to CI + PET/CT (p = 0.005). Moreover, the use of [¹⁸F]F-choline PET/CT was more frequent in patients with higher Gleason score (GS) or ISUP grade (p = 0.013). The type of treatment performed (surgery n = 33; radiation therapy n = 22; surveillance n = 6; multimodality therapy n = 6; systemic therapy n = 13; not available n = 2) did not show any relationship with the modality adopted to stage the disease. [¹⁸F]F-choline PET/CT induced a change of planned therapy in 5/35 patients in group B (14.3%). Moreover, patients investigated with [¹⁸F]F-choline PET/CT alone demonstrated longer biochemical recurrence (BCR)-free survival (30.8 months) in comparison to patients of groups A and B (15.5 and 23.5 months, respectively, p = 0.006), probably due to a more accurate selection of primary treatment. Finally, total lesion choline kinase activity (TLCKA) of the primary lesion, calculated by multiplying metabolic tumor volume and mean standardized uptake value (SUVmean), was able to more effectively discriminate patients who had recurrence after therapy compared to those without (p = 0.03). In our real-world experience [¹⁸F]F-choline PET/CT as a tool for the initial management of PCa had a relevant impact in terms of therapy selection and was associated with longer BCR-free survival. Moreover, TLCKA of the primary lesion looks a promising parameter for predicting recurrence after curative therapy.

Whole-body magnetic resonance imaging: technique, guidelines and key applications

Whole-body magnetic resonance imaging (WB-MRI) is an imaging method without ionising radiation that can provide WB coverage with a core protocol of essential imaging contrasts in less than 40 minutes, and it can be complemented with sequences to evaluate specific body regions as needed. In many cases, WB-MRI surpasses bone scintigraphy and computed tomography in detecting and characterising lesions, evaluating their response to therapy and in screening of high-risk patients. Consequently, international guidelines now recommend the use of WB-MRI in the management of patients with multiple myeloma, prostate cancer, melanoma and individuals with certain cancer predisposition syndromes. The use of WB-MRI is also growing for metastatic breast cancer, ovarian cancer and lymphoma as well as for cancer screening amongst the general population. In light of the increasing interest from clinicians and patients in WB-MRI as a radiation-free technique for guiding the management of cancer and for cancer screening, we review its technical basis, current international guidelines for its use and key applications.

Clinical impact of PET imaging in prostate cancer management

PURPOSE OF REVIEW

Imaging of prostate cancer has been a rapidly evolving field in recent years with the introduction of multiple new PET tracer agents. Introduction of novel imaging techniques into clinical practice requires careful evaluation, with the ultimate aims of improved patient outcomes, better sequencing of treatments, and cost effectiveness. The increased sensitivity and specificity of these new PET agents present both challenges and opportunities. We know they frequently change management, but are these effective management changes, and is it always in the best interests of the patients?

RECENT FINDINGS

This review will focus on recent publications that provide high-level evidence for the use of PET in prostate cancer. It will discuss studies that have evaluated the clinical impact of PET imaging in prostate cancer and will review a number of trials that demonstrate the potential of PET to change current standard of care, from diagnosis, to prognostic capabilities in men with metastatic prostate cancer.

SUMMARY

Evidence for the use of PET in prostate cancer is building with studies evaluating diagnostic accuracy of PET at all stages of prostate cancer. We review the evidence available, focusing on prospective trials that are measuring the impact of new technology on patient outcomes.

Changing the Goal Posts: Prostate-specific Membrane Antigen Targeted Theranostics in Prostate Cancer

OBJECTIVE

Prostate-specific membrane antigen (PSMA) theranostics is changing the face of prostate cancer diagnosis and therapy. PSMA, a transmembrane protein over-expressed in many prostate cancers, is a promising target for theranostics. Theranostics is the concept of small molecule proteins that are labelled to different radionuclides and can be used for either diagnosis or therapy, dependent on whether they are labelled with an imaging or therapy radionuclide. By directly targeting the cancer cells with imaging and then for therapy, this approach embodies the philosophy of precision medicine - right drug, right time, right dose. The question is how to best utilise these new imaging and therapy agents in clinical practice. This review will evaluate the importance of PSMA in prostate cancer, its role in diagnostic imaging, and its potential as a therapy of advanced prostate cancer.

DATA SOURCES

Electronic databases including MEDLINE, Scopus, professional websites were searched.

CONCLUSION

PSMA-directed theranostics has an expanding role in prostate cancer because of its utility as a sensitive diagnostic tool that can be coupled with efficacious and low-toxicity therapeutic options. Ongoing research is required to determine how to use this effective tool for best patient care.

IMPLICATIONS FOR NURSING PRACTICE

PSMA theranostics is rapidly being incorporated into the routine care of men with prostate cancer. Understanding its strengths, its limitations, and where it may be valuable in clinical care is important in undertaking best patient practice.

Imaging diagnosis of metastatic breast cancer

Numerous imaging modalities may be used for the staging of women with advanced breast cancer. Although bone scintigraphy and multiplanar-CT are the most frequently used tests, others including PET, MRI and hybrid scans are also utilised, with no specific recommendations of which test should be preferentially used. We review the evidence behind the imaging modalities that characterise metastases in breast cancer and to update the evidence on comparative imaging accuracy.

A Prospective Study of 18F-DCFPyL PSMA PET/CT Restaging in Recurrent Prostate Cancer following Primary External Beam Radiotherapy or Brachytherapy

PURPOSE

Radio-recurrent prostate cancer is typically detected by a rising prostate-specific antigen and may reflect local or distant disease. Positron emission tomography (PET) radiotracers targeting prostate-specific membrane antigen, such as 18F-DCFPyL have shown promise in restaging men with recurrent disease postprostatectomy but are less well characterized in the setting of radio-recurrent disease.

METHODS AND MATERIALS

A prospective, multi-institutional study was conducted to evaluate the effect of 18F-DCFPyL PET/computed tomography (CT) when added to diagnostic imaging (DI; CT abdomen and pelvis, bone scan, multiparametric magnetic resonance imaging pelvis) for men with radio-recurrent prostate cancer. All men were imaged with DI and subsequently underwent 18F-DCFPyL PET/CT with local and central reads. Tie break reads were performed as required. Management questionnaires were completed after DI and again after 18F-DCFPyL PET/CT. Discordance in patterns of disease detected with 18F-DCFPyL PET/CT versus DI and changes in management were characterized.

RESULTS

Seventy-nine men completed the study. Most men had T1 disease (62%) and Gleason score <7 (95%). Median prostate-specific antigen at diagnosis was 7.4 ng/mL and at relapse was 4.8 ng/mL. DI detected isolated intraprostatic recurrence in 38 out of 79 men (48%), regional nodal recurrence in 9 out of 79 (11%), distant disease in 12 out of 79 (15%), and no disease in 26 out of 79 (33%). 18F-DCFPyL PET/CT detected isolated intraprostatic recurrence in 38 out of 79 men (48%), regional nodal recurrence in 21 out of 79 (27%), distant disease in 24 out of 79 (30%), and no disease in 10 out of 79 (13%). DI identified 8 out of 79 (10%) patients to have oligometastatic disease, compared with 21 out of 79 (27%) with 18F-DCFPyL PET/CT. 18F-DCFPyL PET/CT changed proposed management in 34 out of 79 (43%) patients.

CONCLUSIONS

18F-DCFPyL PET/CT identified extraprostatic disease in twice as many men with radio-recurrent prostate cancer compared with DI and detected a site of recurrence in 87% of men compared with 67% with DI. Furthermore, 18F-DCFPyL PET/CT identified potentially actionable disease (prostate only recurrence or oligometastatic disease) in 75% of men and changed proposed management in 43% of men.

The Contribution of Multiparametric Pelvic and Whole-Body MRI to Interpretation of 18F-Fluoromethylcholine or 68Ga-HBED-CC PSMA-11 PET/CT in Patients with Biochemical Failure After Radical Prostatectomy

Our purpose was to assess whether the addition of data from multiparametric pelvic MRI (mpMR) and whole-body MRI (wbMR) to the interpretation of 18F-fluoromethylcholine (18F-FCH) or 68Ga-HBED-CC PSMA-11 (68Ga-PSMA) PET/CT (=PET) improves the detection of local tumor recurrence or of nodal and distant metastases in patients after radical prostatectomy with biochemical failure. Methods: The current analysis was performed as part of a prospective, multicenter trial on 18F-FCH or 68Ga-PSMA PET, mpMR, and wbMR. Eligible men had an elevated level of prostate-specific antigen (PSA) (>0.2 ng/mL) and high-risk features (Gleason score > 7, PSA doubling time < 10 mo, or PSA > 1.0 ng/mL) with negative or equivocal conventional imaging results. PET was interpreted with mpMR and wbMR in consensus by 2 radiologists and compared with prospective interpretation of PET or MRI alone. Performance measures of each modality (PET, MRI, and PET/mpMR-wbMR) were compared for each radiotracer and each individual patient (for 18F-FCH, or 68Ga-PSMA for patients who had 68Ga-PSMA PET) and to a composite reference standard. Results: There were 86 patients with PET (18F-FCH [n = 76] and/or 68Ga-PSMA [n = 26]) who had mpMR and wbMR. Local tumor recurrence was detected in 20 of 76 (26.3%) on 18F-FCH PET/mpMR, versus 11 of 76 (14.5%) on 18F-FCH PET (P = 0.039), and in 11 of 26 (42.3%) on 68Ga-PSMA PET/mpMR, versus 6 of 26 (23.1%) on 68Ga-PSMA PET (P = 0.074). Per patient, PET/mpMR was more often positive for local tumor recurrence than PET (P = 0.039) or mpMR (P = 0.019). There were 20 of 86 patients (23.3%) with regional nodal metastases on both PET/wbMR and PET (P = 1.0) but only 12 of 86 (14%) on wbMR (P = 0.061). Similarly, there were more nonregional metastases detected on PET/wbMR than on PET (P = 0.683) or wbMR (P = 0.074), but these differences did not reach significance. Compared with the composite reference standard for the detection of disease beyond the prostatic fossa, PET/wbMR, PET, and wbMR had sensitivity of 50%, 50%, and 8.3%, respectively, and specificity of 97.1%, 97.1%, and 94.1%, respectively. Conclusion: Interpretation of PET/mpMR resulted in a higher detection rate for local tumor recurrence in the prostatic bed in men with biochemical failure after radical prostatectomy. However, the addition of wbMR to 18F-FCH or 68Ga-PSMA PET did not improve detection of regional or distant metastases.

Comparison of MRI Sequences in Whole-Body PET/MRI for Staging of Patients With High-Risk Prostate Cancer

OBJECTIVE

The purpose of this study is to investigate the diagnostic value of various MRI sequences used for whole-body (WB) ¹⁸F-fluorocholine (FCH) PET/MRI staging of patients with high-risk prostate cancer (PCa).

SUBJECTS AND METHODS

This analysis is based on data from a prospective study that included 58 patients with untreated high-risk PCa who underwent integrated WB FCH PET/MRI (n = 10) or FCH PET/CT and WB MRI (n = 48). Metastatic sites were recorded. The standard of reference was histopathologic findings or clinical and imaging follow-up, or both. For each MRI sequence (Dixon T1-weighted, turbo inversion recovery magnitude, WB DWI, and gadolinium-enhanced T1-weighted volumetric interpolated breath-hold examination [VIBE]), acquisition time was recorded, and conspicuity of metastatic lesions was qualitatively assessed by two radiologists using a 4-point ordinal scale (0-3).

RESULTS

Total WB acquisition times were 1 minute 25 seconds for Dixon T1-weighted, 15 minutes 7 seconds for turbo inversion recovery magnitude, 16 minutes 33 seconds for WB DWI, and 1 minute 28 seconds for gadolinium-enhanced T1-weighted VIBE. The lesion detection rates were 88.3% (68/77) for Dixon T1-weighted, 94.8% (73/77) for turbo inversion recovery magnitude, 95.2% (40/42) for WB DWI, and 97.4% (75/77) for gadolinium-enhanced T1-weighted VIBE sequences. Moderate or high conspicuity scores were assigned to 62.3% (48/77) of lesions for Dixon T1-weighted, 88.3% (68/77) of lesions for turbo inversion recovery magnitude, 90.5% (38/42) of lesions for WB DWI, and 92.2% (71/77) of lesions for gadolinium-enhanced T1-weighted VIBE sequences. Conspicuity of metastases on gadolinium-enhanced T1-weighted VIBE and WB DWI sequences was higher than that on Dixon T1-weighted sequences (p < 0.0001 and p = 0.0011, respectively).

CONCLUSION

Metastases from prostate cancer are best detected at DWI or gadolinium-enhanced T1-weighted VIBE sequences. The most time-efficient sequence with the highest lesion detection rate and conspicuity is gadolinium-enhanced T1-weighted VIBE.

Comparison of 18F-Choline PET/CT and MRI functional parameters in prostate cancer

AIM

¹⁸F-Choline (FCH) uptake parameters are strong indicators of aggressive disease in prostate cancer. Functional parameters derived by magnetic resonance imaging (MRI) are also correlated to aggressive disease. The aim of this work was to evaluate the relationship between metabolic parameters derived by FCH PET/CT and functional parameters derived by MRI.

MATERIALS AND METHODS

Fourteen patients with proven prostate cancer who underwent FCH PET/CT and multiparametric MRI were enrolled. FCH PET/CT consisted in a dual phase: early pelvic list-mode acquisition and late whole-body acquisition. FCH PET/CT and multiparametric MRI examinations were registered and tumoral volume-of-interest were drawn on the largest lesion visualized on the apparent diffusion coefficient (ADC) map and projected onto the different multiparametric MR images and FCH PET/CT images. Concerning the FCH uptake, kinetic parameters were extracted with the best model selected using the Akaike information criterion between the one- and two-tissue compartment models with an imaging-derived plasma input function. Other FCH uptake parameters (early SUVmean and late SUVmean) were extracted. Concerning functional parameters derived by MRI scan, cell density (ADC from diffusion weighting imaging) and vessel permeability (K_trans and V_e using the Tofts pharmakinetic model from dynamic contrast-enhanced imaging) parameters were extracted. Spearman's correlation coefficients were calculated to compare parameters.

RESULTS

The one-tissue compartment model for kinetic analysis of PET images was selected. Concerning correlation analysis between PET parameters, K₁ was highly correlated with early SUVmean (r = 0.83, p < 0.001) and moderately correlated with late SUVmean (r = 0.66, p = 0.010) and early SUVmean was highly correlated with late SUVmean (r = 0.90, p < 0.001). No significant correlation was found between functional MRI parameters. Concerning correlation analysis between PET and functional MRI parameters, K₁ (from FCH PET/CT imaging) was moderately correlated with K_trans (from perfusion MR imaging) (r = 0.55, p = 0.041).

CONCLUSIONS

No significant correlation was found between FCH PET/CT and multiparametric MRI metrics except FCH influx which is moderately linked to the vessel permeability in prostate cancer.